Combustion, either in internal combustion engines, or in burners and the like, is used widely to convert energy from one form to another. Recently internal combustion engines have been used to burn combustible gases produced from decomposing garbage at, for example, landfill sites. The internal combustion engines are connected to electrical generators and the combustible gases which would otherwise be dissipated in the atmosphere are collected, burned and electrical power generated as a result. In times of rising energy costs, such recovery techniques are both efficient and desirable.
Other power generation techniques involve burning fossil fuels to produce heat, and then steam and then electricity. While some fuels, such as gas, are relatively clean burning, other fuels, such as coal, are very dirty and produce much noxious pollution.
A common feature of power generating combustion sources is their large size. Further, unlike for example, automobiles where the quality of the fuel is closely regulated and generally uniform, the quality of combustible gases from landfill sites and even the quality of coal used to fire generating stations, can vary widely. Thus, to achieve consistent results, such combustion sources tend to burn hotter which in turn tends to produce high temperature exhaust gases, in the order of 500 degrees C. or more. Such large sized and hot combustion sources are also notoriously polluting, partly because they tend to run constantly for long periods.
Catalytic converters are well known devices, used for example in automobile exhaust systems. Such converters include metal catalysts, which facilitate certain beneficial chemical reactions in an exhaust gas stream. Manipulation of the catalytic chemistry can help cause pollution reduction effects on a range of exhaust gases and also eliminate or greatly reduce a range of noxious pollutants, such as semi-burnt or unburnt hydrocarbons, NOX, CO and the like. Modern automobile engines tend to run very cleanly, and thus there is a reduced need for catalytic converters. It would not be uncommon for a catalytic converter to outlast a modern automobile. Further, because vehicle engines tend to only run periodically, there are different pollution control issues than for power generator combustion sources.